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BioRxiv : the Preprint Server For... Jun 2024Duchenne muscular dystrophy (DMD) is marked by the genetic deficiency of the dystrophin protein in striated muscle whose consequence is a cascade of cellular changes...
Duchenne muscular dystrophy (DMD) is marked by the genetic deficiency of the dystrophin protein in striated muscle whose consequence is a cascade of cellular changes that predispose the susceptibility to contraction injury central to DMD pathology. Recent evidence identified the proliferation of microtubules enriched in post-translationally modified tubulin as a consequence of dystrophins absence that increases the passive mechanics of the muscle fiber and the excess mechanotransduction elicited reactive oxygen species and calcium signals that promote contraction injury. Motivated by evidence that acutely normalizing the disease microtubule alterations reduced contraction injury in murine DMD muscle ( ), here we sought the direct impact of these microtubule alterations independent of dystrophins absence and the multitude of other changes consequent to dystrophic disease. To this end we used acute pharmacologic (epithiolone-D, EpoD; 4 hours) or genetic (vashohibin-2 and small vasohibin binding protein overexpression via AAV9; 2 weeks) strategies to effectively model the proliferation of detyrosination enriched microtubules in the muscle. Quantifying nerve evoked plantarflexor function we find no alteration in peak torque nor contraction kinetics in WT mice modeling these DMD relevant MT alterations. Quantifying the susceptibility to eccentric contraction injury we show EpoD treatment proffered a small but significant protection from contraction injury while VASH/SVBP had no discernable impact. We conclude that the disease dependent MT alterations act in concert with additional cellular changes to predispose contraction injury in DMD.
PubMed: 38948772
DOI: 10.1101/2024.06.19.599775 -
Journal of Multidisciplinary Healthcare 2024Despite over 30 years of microbiome and skeletal muscle research, no quantitative analysis of sarcopenia and the microbiome literature had been conducted. Our... (Review)
Review
Despite over 30 years of microbiome and skeletal muscle research, no quantitative analysis of sarcopenia and the microbiome literature had been conducted. Our bibliometric study examined research status, hotspots, and future trends. We utilized bibliometric techniques to search the Science Citation Index Extended Database on February 27, 2023, using the Bibliometrix package in R to create a map displaying scientific production and subject categories. Collaborative network maps between countries/regions were visualized using Scimago Graphica, while VOSviewer explored collaboration modes among individuals and institutions. We analyzed the top 25 emerging keywords, top co-occurring keyword networks, and co-occurring keyword clusters using CiteSpace. A total of 997 articles were retrieved for sarcopenia and microbiome, of which 633 papers were analyzed. Both the number of publications and total citation frequency had been continuously increasing. The United States had the highest total citation frequency, while China had the highest number of publications. Research on the impact of the microbiome on sarcopenia was in its nascent stage and spans multiple disciplines, including nutrition, microbiology, geriatrics, immunology, endocrinology and metabolism, molecular biology, and sports medicine. The University of Copenhagen contributed the most to the number of publications (n=16), with Tibbett M (n=7) and Hulver MW (n=7) among the top authors. The most published journal was "Nutrients" (n=24). Analysis of keywords and clusters revealed new research hotspots in microbes and sarcopenia, such as malnutrition, dietary fiber, signaling pathways, frailty, and intestinal permeability. Research on the impact of the microbiome on sarcopenia is in its infancy and spans multiple disciplines. Malnutrition, dietary fiber, signaling pathways, frailty, and intestinal microbes are currently research hotspots. Furthermore, the visual atlas analysis of research on microbes and sarcopenia helps to track the knowledge structure in research fields related to sarcopenia and microbes, providing direction for future research.
PubMed: 38948393
DOI: 10.2147/JMDH.S469747 -
Regenerative Therapy Jun 2024Skeletal muscle injury (SMI) is often treated conservatively, although it can lead to scar tissue formation, which impedes muscle function and increases muscle re-injury...
BACKGROUND
Skeletal muscle injury (SMI) is often treated conservatively, although it can lead to scar tissue formation, which impedes muscle function and increases muscle re-injury risk. However, effective interventions for SMIs are yet to be established.
HYPOTHESIS
The administration of Silk Elastin® (SE), a novel artificial protein, to the SMI site can suppress scar formation and promote tissue repair.
STUDY DESIGN
A controlled laboratory study.
METHODS
: Fibroblast migration ability was assessed using a scratch assay. SE solution was added to the culture medium, and the fibroblast migration ability was compared across different concentrations. : An SMI model was established with Sprague-Dawley rats, which were assigned to three groups based on the material injected to the SMI site: SE gel (SE group; n = 8), atelocollagen gel (Atelo group; n = 8), and phosphate buffer saline (PBS group; n = 8). Histological evaluations were performed at weeks 1 and 4 following the SMI induction. In the 1-week model, we detected the expression of transforming growth factor (TGF)-β1 in the stroma using immunohistological evaluation and real-time polymerase chain reaction analysis. In the 4-week model, we measured tibialis anterior muscle strength upon peroneal nerve stimulation as a functional assessment.
RESULTS
: The fibroblast migration ability was suppressed by SE added at a concentration of 10⁴ μg/mL in the culture medium. : In the 1-week model, the SE group exhibited significantly lower TGFβ -1 expression than the PBS group. In the 4-week model, the SE group had a significantly larger regenerated muscle fiber diameter and smaller scar formation area ratio than the other two groups. Moreover, the SE group was superior to the other two groups in terms of regenerative muscle strength.
CONCLUSION
Injection of SE gel to the SMI site may inhibit tissue scarring by reducing excessive fibroblast migration, thereby enhancing tissue repair.
CLINICAL RELEVANCE
The findings of this study may contribute to the development of an early intervention method for SMIs.
PubMed: 38948131
DOI: 10.1016/j.reth.2024.05.012 -
World Journal of Stem Cells Jun 2024Pulmonary fibrosis (PF) is a chronic interstitial lung disease characterized by fibroblast proliferation and extracellular matrix formation, causing structural damage...
BACKGROUND
Pulmonary fibrosis (PF) is a chronic interstitial lung disease characterized by fibroblast proliferation and extracellular matrix formation, causing structural damage and lung failure. Stem cell therapy and mesenchymal stem cells-extracellular vesicles (MSC-EVs) offer new hope for PF treatment.
AIM
To investigate the therapeutic potential of MSC-EVs in alleviating fibrosis, oxidative stress, and immune inflammation in A549 cells and bleomycin (BLM)-induced mouse model.
METHODS
The effect of MSC-EVs on A549 cells was assessed by fibrosis markers [collagen I and α-smooth muscle actin (α-SMA), oxidative stress regulators [nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1), and inflammatory regulators [nuclear factor-kappaB (NF-κB) p65, interleukin (IL)-1β, and IL-2]. Similarly, they were assessed in the lungs of mice where PF was induced by BLM after MSC-EV transfection. MSC-EVs ion PF mice were detected by pathological staining and western blot. Single-cell RNA sequencing was performed to investigate the effects of the MSC-EVs on gene expression profiles of macrophages after modeling in mice.
RESULTS
Transforming growth factor (TGF)-β1 enhanced fibrosis in A549 cells, significantly increasing collagen I and α-SMA levels. Notably, treatment with MSC-EVs demonstrated a remarkable alleviation of these effects. Similarly, the expression of oxidative stress regulators, such as Nrf2 and HO-1, along with inflammatory regulators, including NF-κB p65 and IL-1β, were mitigated by MSC-EV treatment. Furthermore, in a parallel manner, MSC-EVs exhibited a downregulatory impact on collagen deposition, oxidative stress injuries, and inflammatory-related cytokines in the lungs of mice with PF. Additionally, the mRNA sequencing results suggested that BLM may induce PF in mice by upregulating pulmonary collagen fiber deposition and triggering an immune inflammatory response. The findings collectively highlight the potential therapeutic efficacy of MSC-EVs in ameliorating fibrotic processes, oxidative stress, and inflammatory responses associated with PF.
CONCLUSION
MSC-EVs could ameliorate fibrosis and by downregulating collagen deposition, oxidative stress, and immune-inflammatory responses.
PubMed: 38948098
DOI: 10.4252/wjsc.v16.i6.670 -
Journal of Electrical Bioimpedance Jan 2024The detection of meat quality defects can involve both subjective and objective methods. PSE-like meat is linked to a common pork defect and can be caused by rapid...
The detection of meat quality defects can involve both subjective and objective methods. PSE-like meat is linked to a common pork defect and can be caused by rapid post-mortem damage of muscle fibers. This damage can again be linked to various factors, such as a low ultimate pH or a higher slaughter weight. PSE-like defects are characterized by discoloration, structural damage, and excessive moisture loss. However, the lack of suitable instrument-based methods makes the detection of PSE-like defects difficult, and subjective methods typically suffer from poorer reproducibility. The objective of this study was to establish how subjective visual evaluation correlates with electrical impedance spectroscopy and with traditional quality parameters. To do so, visual scoring was performed together with measurements of bioimpedance, color, and pH in two ham muscles (Adductor, Semimembranosus) for 136 animals 24-hours post-mortem. When comparing with visual scoring, Pearson correlation analysis shows the strongest correlation for bioimpedance ( , r = -0.46, R = 21%), followed by pH (r = 0.44, R = 19%). When using all five quality measures, i.e., , pH, and CIELAB , the multivariate regression model had a prediction error of 0.76 for the visual scores. This was close to the error describing the subjective bias of visual scoring, more specifically the prediction error between the two observers (0.85). In all, showed the strongest correlation among instrument-based quality tests and alone may be used for predicting pork ham structural defects, i.e., as an instrument-based alternative for subjective, visual scoring. However, an instrument that combines with pH and/or *** would improve the prediction of PSE-like quality defects.
PubMed: 38947175
DOI: 10.2478/joeb-2024-0008 -
MedRxiv : the Preprint Server For... Jun 2024Inclusion body myositis (IBM) is the most prevalent muscle disease in adults for which no current treatment exists. The pathogenesis of IBM remains poorly defined....
BACKGROUND
Inclusion body myositis (IBM) is the most prevalent muscle disease in adults for which no current treatment exists. The pathogenesis of IBM remains poorly defined. Inflammation and mitochondrial dysfunction are the most common histopathological findings. In this study, we aimed to explore the interplay between inflammation and mitochondrial dysfunction in IBM patients, highlighting sex differences.
METHODS
We included 38 IBM patients and 22 age- and sex-matched controls without myopathy. Bulk RNA sequencing, Meso Scale Discovery ELISA, western blotting, histochemistry and immunohistochemistry were performed on frozen muscle samples from the study participants.
RESULTS
We demonstrated activation of the NLRP3 inflammasome in IBM muscle samples, with the NLRP3 inflammasome pathway being the most upregulated. On muscle histopathology, there is increased NRLP3 immunoreactivity in both inflammatory cells and muscle fibers. Mitophagy is critical for removing damaged mitochondria and preventing the formation of a vicious cycle of mitochondrial dysfunction-NLRP3 activation. In the IBM muscle samples, we showed altered mitophagy, most significantly in males, with elevated levels of p-S65-Ubiquitin, a mitophagy marker. Furthermore, p-S65-Ubiquitin aggregates accumulated in muscle fibers that were mostly type 2 and devoid of cytochrome-c-oxidase reactivity. Type 2 muscle fibers are known to be more prone to mitochondrial dysfunction. levels correlated with p-S65-Ubiquitin levels in both sexes but with loss of in muscle strength only in males. Finally, we identified sex-specific molecular pathways in IBM, with females having activation of pathways that could offset some of the pathomechanisms of IBM.
CONCLUSIONS
NLRP3 inflammasome is activated in IBM, along with altered mitophagy particularly in males, which is of potential therapeutic significance. These findings suggest sex-specific mechanisms in IBM that warrant further investigation.
PubMed: 38947067
DOI: 10.1101/2024.06.15.24308845 -
Research Square Jun 2024Interstitial cells of Cajal (ICC) and PDGFRα cells regulate smooth muscle motility in the gastrointestinal (GI) tract. However, their role(s) in esophageal motility...
Interstitial cells of Cajal (ICC) and PDGFRα cells regulate smooth muscle motility in the gastrointestinal (GI) tract. However, their role(s) in esophageal motility are still unclear. The mouse esophagus has traditionally been described as almost entirely skeletal muscle in nature though ICC have been identified along its entire length. The current study evaluated the distribution of skeletal and smooth muscle within the esophagus using a mouse selectively expressing eGFP in smooth muscle cells (SMCs). The relationship of SMCs to ICC and PDGFRα cells was also examined. SMCs declined in density in the oral direction however SMCs represented ~ 25% of the area in the distal esophagus suggesting a likeness to the transition zone observed in humans. ANO1 intramuscular ICC (ICC-IM) were distributed along the length of the esophagus though like SMCs, declined proximally. ICC-IM were closely associated with SMCs but were also found in regions devoid of SMCs. Intramuscular and submucosal PDGFRα cells were densely distributed throughout the esophagus though only intramuscular PDGFRα cells within the LES and distal esophagus highly expressed SK3. ICC-IM and PDGFRα cells were closely associated with nNOS , VIP , VAChT and TH neurons throughout the LES and distal esophagus. GFAP cells resembling intramuscular enteric glia were observed within the muscle and were closely associated with ICC-IM and PDGFRα cells, occupying a similar location to motor nerve fibers. These data suggest that the mouse esophagus is more similar to the human than thought previously and thus set the foundation for future functional and molecular studies using transgenic mice.
PubMed: 38947055
DOI: 10.21203/rs.3.rs-4474290/v1 -
Physiological Reports Jul 2024Cancer cachexia is a multifactorial syndrome associated with advanced cancer that contributes to mortality. Cachexia is characterized by loss of body weight and muscle...
Cancer cachexia is a multifactorial syndrome associated with advanced cancer that contributes to mortality. Cachexia is characterized by loss of body weight and muscle atrophy. Increased skeletal muscle mitochondrial reactive oxygen species (ROS) is a contributing factor to loss of muscle mass in cachectic patients. Mice inoculated with Lewis lung carcinoma (LLC) cells lose weight, muscle mass, and have lower muscle sirtuin-1 (sirt1) expression. Nicotinic acid (NA) is a precursor to nicotinamide dinucleotide (NAD+) which is exhausted in cachectic muscle and is a direct activator of sirt1. Mice lost body and muscle weight and exhibited reduced skeletal muscle sirt1 expression after inoculation with LLC cells. C2C12 myotubes treated with LLC-conditioned media (LCM) had lower myotube diameter. We treated C2C12 myotubes with LCM for 24 h with or without NA for 24 h. C2C12 myotubes treated with NA maintained myotube diameter, sirt1 expression, and had lower mitochondrial superoxide. We then used a sirt1-specific small molecule activator SRT1720 to increase sirt1 activity. C2C12 myotubes treated with SRT1720 maintained myotube diameter, prevented loss of sirt1 expression, and attenuated mitochondrial superoxide production. Our data provides evidence that NA may be beneficial in combating cancer cachexia by maintaining sirt1 expression and decreasing mitochondrial superoxide production.
Topics: Animals; Cachexia; Sirtuin 1; Muscle Fibers, Skeletal; Mice; Oxidative Stress; Mice, Inbred C57BL; Carcinoma, Lewis Lung; Male; Heterocyclic Compounds, 4 or More Rings; Mitochondria, Muscle; Cell Line; Niacin; Mitochondria; Reactive Oxygen Species
PubMed: 38946587
DOI: 10.14814/phy2.16103 -
Journal of Cellular Physiology Jun 2024Skeletal muscle is crucial for animal movement and posture maintenance, and it serves as a significant source of meat in the livestock and poultry industry. The number...
Skeletal muscle is crucial for animal movement and posture maintenance, and it serves as a significant source of meat in the livestock and poultry industry. The number of muscle fibers differentiated from myoblast in the embryonic stage is one of the factors determining the content of skeletal muscle. Insulin-like growth factor 2 (IGF2), a well-known growth-promoting hormone, is crucial for embryonic and skeletal muscle growth and development. However, the specific molecular mechanism underlying its impact on chicken embryonic myoblast differentiation remains unclear. To elucidate the molecular mechanism by which IGF2 regulates chicken myoblast differentiation, we manipulated IGF2 expression in chicken embryonic myoblast. The results demonstrated that IGF2 was upregulated during chicken skeletal muscle development and myoblast differentiation. On the one hand, we found that IGF2 promotes mitochondrial biogenesis through the PGC1/NRF1/TFAM pathway, thereby enhancing mitochondrial membrane potential, oxidative phosphorylation, and ATP synthesis during myoblast differentiation. This process is mediated by the PI3K/AKT pathway. On the other hand, IGF2 regulates BNIP3-mediated mitophagy, clearing dysfunctional mitochondria. Collectively, our findings confirmed that IGF2 cooperatively regulates mitochondrial biogenesis and mitophagy to remodel the mitochondrial network and enhance mitochondrial function, ultimately promoting myoblast differentiation.
PubMed: 38946060
DOI: 10.1002/jcp.31351 -
Muscle-Protective Effect of Carnosine against Dexamethasone-Induced Muscle Atrophy in C2C12 Myotube.Journal of Nutritional Science and... 2024This study investigated the protective effect of carnosine and its components (L-histidine and β-alanine [HA]) against dexamethasone (Dex)-induced muscle atrophy in...
This study investigated the protective effect of carnosine and its components (L-histidine and β-alanine [HA]) against dexamethasone (Dex)-induced muscle atrophy in C2C12 myotubes. Myotubes were treated with Dex (10 μM) to induce muscle atrophy manifested by decreased myotube diameter, low myosin heavy chain content, and increased expression of muscle atrophy-associated ubiquitin ligases (Atrogin-1, MuRF-1, and Cbl-b). Carnosine (20 mM) treatment significantly improved the myotube diameter and MyHC protein expression level in Dex-treated C2C12 myotubes. It also downregulated the expression of Atrogin-1, MuRF-1, and Cbl-b and suppressed the expression of forkhead box O3 (FoxO3a) mediated by Dex. Furthermore, reactive oxygen species production was increased by Dex but was ameliorated by carnosine treatment. However, HA (20 mM), the component of carnosine, treatment was found ineffective in preventing Dex-induced protein damage. Therefore, based on above results it can be suggested that carnosine could be a potential therapeutic agent to prevent Dex-induced muscle atrophy compared to its components HA.
Topics: Carnosine; Dexamethasone; Muscular Atrophy; Muscle Fibers, Skeletal; Animals; Mice; Muscle Proteins; Cell Line; Reactive Oxygen Species; SKP Cullin F-Box Protein Ligases; Ubiquitin-Protein Ligases; Forkhead Box Protein O3; Tripartite Motif Proteins; Myosin Heavy Chains
PubMed: 38945887
DOI: 10.3177/jnsv.70.219